General Information

Contents

Cerebral palsy

Cerebral palsy is the most common physical disability in childhood. Historically the rate of cerebral palsy has been reported as between 2 and 2.5 people per thousand live births in the developed world [2, 8].

Definition of cerebral palsy

The definition of cerebral palsy the QCPR uses is the same definition used by the Australian Cerebral Palsy Register and all other Australian state and territory cerebral palsy registers. Cerebral palsy:

1. Is an umbrella term for a group of disorders 2. Is a condition that is permanent but not unchanging 3. Involves a disorder of movement and/or posture and of motor function 4. Is due to a non-progressive interference, lesion, or abnormality, and 5. The interference, lesion, or abnormality originates in the immature brain [1].

This definition is supported by experts within all Australian registers as the most valid and useful definition of cerebral palsy available. It includes key elements from published definitions by Bax [2], Mutch [3] and Rosenbaum [7].

The use of a consistent definition allows data from across all Australian registers to be pooled to create the single largest collection of data from people with cerebral palsy from contiguous jurisdictions in the world. The significance of this data source cannot be underestimated; it will be used to explore the causes of cerebral palsy and methods of prevention and amelioration once the injury has been sustained.

Classification of cerebral palsy

A person’s presentation of cerebral palsy has traditionally been described according to two categories: motor type and motor distribution. • Motor type refers to the type of movement disorder a person has, for example: spasticity, dyskinesia and hypotonia. • Distribution refers to which limbs are involved. Combining both motor type and distribution allows the following classifications:

Spasticity

Spastic cerebral palsy involves very tight muscle tone causing stiff or jerky movements. Spasticity can be distributed predominantly on one side of the body (hemiplegia); affecting the legs more than the arms (diplegia); affecting both legs and particularly one arm (triplegia); or affecting both arms and legs with the arms more affected or equally affected than the legs (quadriplegia).

Dyskinesia

Dyskinetic cerebral palsyis where muscle tone fluctuates or changes causing difficulty with control and co-ordination of movements. This category includes both athetosis and dystonia.

Ataxia

Hypotonia

Hypotonic cerebral palsyrequires low muscle tone in the presence of increased stretch reflexes. Hypotonia associated with intellectual impairment and conditions such as Autism do not exhibit increased stretch reflexes and are therefore not included in this category.

These descriptions remain very important to understanding cerebral palsy. Cerebral palsy is by definition a group of different disorders with different presentations that have different findings on brain imaging [5]. It is likely that different presentations have different causal pathways and it is therefore likely they will be susceptible to different methods of prevention. Additionally, our understanding of how brain injury affects function is still improving [6] and therefore the different presentations of cerebral palsy will possibly require different methods of intervention.

Recent advancements have seen the development of additional methods to describe aspects of a person’s presentation of cerebral palsy. The Gross Motor Function Classification System (GMFCS) categorises the level of gross motor function achieved by children with cerebral palsy, for example the ability to sit and walk, or the need to use a walker or wheelchair. Research has shown that there are strong relationships between a child’s GMFCS level and many aspects of development and function [4]. The usefulness of this classification system has seen it become routinely reported in clinical and scientific endeavour.

Aside from these two main classification systems, the individual presentations and experiences of people with cerebral palsy are also impacted by varying abilities related to vision, hearing, speech or language, intellectual status, as well as the presence of epilepsy.

Frequent questions

How common was cerebral palsy in Queensland among those born between 1996 and 2005?

In total, 881 people with cerebral palsy have been registered for the birth years 1996 to 2005. Of these, 702 were born in Queensland and 801 were admitted to a Queensland hospital in the neonatal period. If all 881 people are included, the crude prevalence of cerebral palsy in Queensland is 1.8 per thousand live births. This is the method that was used in the previous report detailing our 1996 birth year report.

Using only those children who were born in Queensland or were treated in a Queensland hospital during the neonatal period the prevalence of children with cerebral palsy on the register in Queensland is 1.6 per thousand live births.

What was the spread of motor type and motor distribution in Queensland among those born between 1996 to 2005?

Spastic motor type presentation accounts for 87% of all children with cerebral palsy on the register born between 1996 and 2005. This consisted of 30% spastic hemiplegia or monoplegia, 36% spastic diplegia, 2% spastic triplegia and 20% spastic quadriplegia. Additionally, 4% had ataxia, 6% had dyskinesia (more with dystonia than athetosis) and 3% were classified as having hypotonia.

What are the effects of cerebral palsy?

Of all children with cerebral palsy on the register born between 1996 and 2005, the vast majority (87%) have spastic motor type. Spasticity makes movement and coordination difficult due to an increase in muscle tone and heightened response to movements. Further, 28% of children with cerebral palsy born between 1996 and 2005 could not walk functionally or could not walk at all and classified as Gross Motor Function Classification System (GMFCS) level IV or GMFCS level V. Nevertheless, 55% of children with cerebral palsy were able to independently walk and managed stairs or rough surfaces with a rail by the age of five years and classified as GMFCS level I or GMFCS level II.

Other impairments

Children with cerebral palsy were likely to have other impairments in addition to their motor disability.

Vision

There were 54% with some visual impairment and 6% who were functionally blind. Almost all children who were functionally blind were either GMFCS level IV or GMFCS level V and 67% had spastic quadriplegia. With the exception of spastic quadriplegia, between 50% and 60% of children with all motor type classifications have no visual impairment.

Intellectual ability

There were 39.3% of children with cerebral palsy who had no or probably no intellectual impairment, while 31% had a moderate to severe intellectual impairment. The higher the child’s GMFCS level, the more likely it was they had no, or probably no, intellectual impairment. For those children with GMFCS level I, 36% had some level of intellectual impairment. Of children classified as GMFCS level V, 88% had some level of intellectual impairment.

Epilepsy

At age five, 30% of children with cerebral palsy born between 1996 and 2005 had epilepsy. The higher the child’s GMFCS level, the more likely it was they had epilepsy at age five. For children with GMFCS level I, 14% had epilepsy at age 5. For those children with GMFCS level V, 67% had epilepsy. Of all children with spastic triplegia or quadriplegia, 59% also had epilepsy at age 5.

Hearing

Thirteen percent of all children with cerebral palsy born in Queensland between 1996 and 2005 were recorded as having some hearing impairment and 3% were bilaterally deaf (including those who are now able to hear with cochlear implants).

Identified risk factors

This analysis of the data held on the QCPR identified the following factors that were associated with increased rates of cerebral palsy.

Male

In Queensland, 57% of children with cerebral palsy born between 1996 and 2005, were male.

Preterm birth

In Queensland, 49% of children with cerebral palsy born between 1996 and 2005 had a gestational age at delivery less than 37 completed weeks. There was 33 times the rate of cerebral palsy in children born prior to 28 weeks completed gestation compared with those children born between 37 and 41 weeks completed gestation.

Low birth weight

Being born with a low birth weight can result from premature birth or a slow rate of intrauterine growth. In Queensland between 1996 and 2005, 46% of all children with cerebral palsy and were born with a birth weight under 2500 grams. The rate of cerebral palsy for children born smaller than 1500 grams was 32 times higher than for those children born larger than 2500 grams.

Multiple births

In Queensland, 6% of children born between 1996 and 2005, were the product of a multiple birth. Children born one of twins were 8 times more likely to have cerebral palsy than singletons and children born as triplets or higher plurality were 30.1 times more likely to have cerebral palsy than singletons.

Indigenous status

Six percent of children with cerebral palsy (1997-2005) were born to mothers who identified as Aboriginal or both Aboriginal and Torres Strait Islander. Only 4.6% of all children born in Queensland in the same period were born to mothers who identified as Aboriginal or both Aboriginal and Torres Strait Islander